In biblical times, a good name meant more than a good reputation. People understood that a name expressed the essence or identity of a person.
In the Near East, a person's name identified something about their character or circumstances, such as birth or family. Genesis 17:17 provides an illustration of this practice: Sarah and Abraham named their son 'Isaac,' which means 'he laughs.' When God told 100-year-old Abraham that his 90-year-old wife would give birth, he laughed.
Because names were so significant in biblical times, the power to name someone or something demonstrated authority. Genesis 17:1-5 gives an account of God's authority when he changed Abram's name to Abraham. Similarly, Pharaoh conveyed his authority over Joseph when he renamed Joseph as Zaphenath-Paneah (Gen. 41:45).
When God told Moses, 'I know you by name' (Ex. 33:17), God was declaring that he recognized Moses for who he was, his character, circumstances, and identity. God still knows each of his believers by name; he completely understands who and what we are.